Re: Issue with bgworker, SPI and pgstat_report_stat

On 11 July 2016 at 11:49, Michael Paquier <michael(dot)paquier(at)gmail(dot)com> wrote:

> On Mon, Jul 11, 2016 at 3:36 AM, Julien Rouhaud
> <julien(dot)rouhaud(at)dalibo(dot)com> wrote:
> > I'm not opposed, but in this case we should also provide a proper
> > documentation of all the required actions to mimick normal backends.
>
> I'd rather just add a note like "Have a look at PostgresMain if you
> want to imitate a backend able to run queries!" instead of listing all
> the actions doable. If low-level things are added or removed in the
> future in PostgresMain, it is very likely that the documentation will
> not be updated at the same time, killing its purpose at the end.

That sounds like a bug breeding ground. Especially with extensions whose
bgworkers operate across Pg versions, extensions that get updated without
re-checking PostgresMain and don't notice some new housekeeping task, etc.

Rather than encouraging every extension author to copy and paste random
chunks of PostgresMain, probably incorrectly, I really think factoring the
required logic out into something reusable by bgworkers is going to be the
way to go.

--
Craig Ringer http://www.2ndQuadrant.com/
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